Offset size adjustment circuit for grinding machines

ABSTRACT

An automatic machine, which includes a gage mechanism, for grinding workpieces having axially spaced portions of different diameters is disclosed. The gage mechanism, which is used to determine the diameter of each workpiece portion to assure that the workpiece is within certain tolerances, includes a workpiece engaging element or caliper of the chordal type which supplies a signal, indicative of the sensed diameter of a workpiece portion, to a summing network. The summing network also receives a signal from a digital to analog converter arranged to convert a digital signal from a card reader into an analog signal indicative of a desired diameter of a workpiece portion. An analog size offset circuit is arranged to supply an offset signal to the digital to analog converter. The offset circuit provides, in addition to a settable common offset signal, an additional programmed offset signal which is derived from a second analog to digital converter supplied with digital signals from thumbwheel switches which receive enabling signals from a program sequence controller. The controller also supplies enabling signals to the card reader associated with the first-mentioned digital to analog converter.

United States Patent Schoonover et a1.

1541 OFFSET SIZE ADJUSTMENT CIRCUIT [21] Appl. No.: 73,331

I52] 11.8. CI ..5l/l65.7l, 51/165.9l

I51 I Int. Cl. ..B24b 49/06 [58] Field of Search...5 1/165 R, 165 TP,165.71,

[56] References Cited UNITED STATES PATENTS 3,157,971 11/1964 Snyder..5l/165.91 3,466,976 9/1969 Price ..51/165 R 3,557,495 l/1971 Price..5l/165.8

Primary Examiner-Harold D. Whitehead Attorney-Diller, Brown, Ramik &Holt 51 Oct. 3, 1972 [57] ABSTRACT An automatic machine, which includesa gage mechanism, for grinding workpieces having axially spaced portionsof different diameters is disclosed. The gage mechanism, which is usedto determine the diameter of each workpiece portion to assure that theworkpiece is within certain tolerances, includes a workpiece engagingelement or caliper of the chordal type which supplies a signal,indicative: of the sensed diameter of a workpiece portion, to a summingnetwork. The summing network also receives a signal from a digital toanalog converter arranged to convert a digital signal from a card readerinto an analog signal indicative of a desired diameter of a workpieceportion. An analog size offset circuit is arranged to supply an offsetsignal to the digital to analog converter. The offset circuit provides,in addition to a settable common offset signal, an additional programmedoffset signal which is derived from a second analog to digital convertersupplied with digital signals from thumbwheel switches which receiveenabling signals from a program sequence controller. The controller alsosupplies enabling signals to the card reader associated with thefirst-mentioned digital to analog converter.

21 Claims, 10 Drawing Figures PATENTEUnma m2 3.594.970

SHEEI 1 OF 6 INVENTORS STRNLEY C. SCHUDNDVER 2 LESTER RLUCKENBPCHPATENTEUUBTS I972 3.694.970

SHEEI 2 OF 6 INVENTURS STRNLEY C. SCHDDNDVER 8 LESTER .LUCKENBRCHPATENTEDncra m2 SHEET 3 0F 6 PROGRAM SEQ! NC E CONTROLLER GAGE LEFT 2301 THUMBIUHEEL SllllTCHES CARD READER DVERSlZE DIGlTAL "TD mmLne 2CONVERTER ANALOG- SIZE OFFSET raw/202 DlGlTRL TU A n n r 'ZD Ill DIALSWITCHES RNRLDG CONV ERTER nunLoe ROUGH ":HZE TOLERANCE amass JuanQURUFY UND RSRE if}? E Q 2% FINE METER 5\ZE TO 203 (SUMMWG NammQlINVENTDRS STRNLEY cseunuuuvzk S- LESTER R. LUCKENBQCH MRCHNE CONT ROI...

DENEYS OFFSET SIZE ADJUSTMENT CIRCUIT FOR GRINDING MACHINES Thisinvention relates, in general, to new and useful improvements inautomatic machine tools, particularly grinding machines for grindingworkpieces having axially spaced portions of different diameter sizes.More particularly, the invention relates to grinding machines whichinclude a transducer or gaging probe of a chordal-type caliper gage. Anoffset switching arrangement automatically provides a predeterminedamount of oversize from the nominal programmed size for each diameterduring the first automatic cycle of operation. Thumbwheel switchesprovide manual control adjustments for minor size variations for eachdiameter or station of the workpiece to compensate for an undersize oran oversize direction of adjustment.

Prior to this invention, a single offset dial control member wasutilized to provide means for varying the size of each workpiecediameter during a set-up operation by a predetermined amount, before thesemi-automatic or automatic grinding operation. However, the only methodof providing a size variation for a particular diameter was to alter theprogrammed dimension by changing a decade dial which was furnished foreach numeral to alter selectively each of the programmed dimensions.

It has been also known, in grinding machines which utilize card readersto establish programmed dimensions, to provide a special set-up cardwhich provided for a given amount of oversize for each diameter duringthe first automatic grinding cycle. In this particular prior artarrangement, it was not possible to vary the size for each particulardiameter without altering the programmed card or providing card orproviding a new programmed card.

The primary object of this invention is to provide an offset means tocompensate for resulting errors between the programmed size and theactual measurement of each workpiece portion.

Another object of this invention is to provide an offset means tocorrect any existing patterns of size irregularities which areundesirable.

A further object of this invention is to provide an offset means tocompensate for workpiece variations caused by irregular size control orthe flexible properties of a workpiece.

Yet another object of this invention is to provide an offset means tocorrect for minor workpiece changes without altering a programmed cardor providing a new programmed card.

Yet a further object of this invention is to provide a circuit forproducing offset signals in accordance with a program.

Still another object of this invention is to provide a circuit forproducing offset signals in accordance with a program and for producinga base offset signal which may be combined with the offset signals whichare programmed.

With the above and other objects in view, as will hereinafter appear,the nature and features of the invention will be more clearly understoodby reference to the following detailed description, the appended claims,and the several views illustrated in the accompanying drawings in whichlike reference characters designate like parts.

IN THE DRAWINGS:

FIG. 1 is a front elevational view of a grinding machine, andillustrates a gage mechanism positioned adjacent a large diameterportion of a multidiameter workpiece.

FIG. 2 is an end elevational view of the grinding machine of FIG. 1, andshows a chordal type caliper of the gage mechanism in contact with theworkpiece.

FIG. 3 is an enlarged fragmentary side elevational view of the gagemechanism, and illustrates a suitable linkagearrangement and actuatingmeans for advancing the caliper against the workpiece with the axis ofthe probe in a near horizontal line close to or passing through thecenter line of the workpiece so that upper and lower shoes of the gageengage the workpiece with equal force.

FIG. 4 is a fragmentary end view of the gage mechanism of FIG. 3 lookingfrom right-to-left, and more clearly illustrates portions of the linkagearrangement.

FIG. 5 is an end view of the face of the gage of FIGS. 3 and 4, and moreclearly illustrates the details of the upper and lower shoes and theprobe therebetween.

FIG. 6 is a fragmentary top plan view of a gage mounting and locatingmechanism, and the association thereof with a pair of switches forming aportion of the circuitry of FIG. 9.

FIG. 8 is a highly schematic view of the gage mechanism, the mountingthereof, and a hydraulic system for imparting movement to the gagemechanism incidental to a gaging operation.

FIG. 8 is a block and partially schematic diagram of the electroniccircuit of the present invention, including offset means, forcontrolling the grinding cycle of the grinding machine in accordancewith the unground dimension of a work portion in position for grinding.

FIG. 9 is a schematic view of an electrical circuit operable incooperation with the gaging mechanism and the circuit illustrated inFIG. 8 for controlling the grinding cycle.

FIG. 10 is a block and partially schematic diagram of an illustrativeembodiment of an analog offset circuit suitable for use in theelectronic circuit illustrated in FIG. 8, and shows details of itsconnection thereto.

Referring first to FIGS. 1 and 2, a workpiece W having portions Athrough E of different diameters is mounted between a headstock l3 and atailstock 14 of an automatic grinding machine 10 which is of aconventional construction and includes a conventional bed 11.

The bed 11 has mounted thereon, in a conventional manner forlongitudinal sliding movement, a work carriage or support 12. Theheadstock 13 is mounted at one end of the support 12 and includes aconventional drive (not illustrated) to rotate the workpiece W. Thetailstock 14 is mounted on the opposite end of the support 12, as isclearly illustrated in FIG. 1. The workpiece W is rotated by theheadstock 13 about a predetermined axis and is shifted longitudinallywith the support 12 in a conventional manner. For the purpose ofillustration, longitudinal shifting of the support 12 may be effected bya hand wheel 15. It is to be understood, however, that support 12 may beshifted by different means such as, for example, a drive device underthe control of a program sequence controller 200.

A punch card (not shown) housed in a conventional card reader 201 (FIG.8) provides a signal to position the selected portion of the workpiece Wwhich is to be ground, during a particular period of a grinding cycle,longitudinally of the grinding wheel 17, as will be described more fullyhereinafter. As the support 12 is shifted longitudinally a transducer18, driven by the support 12, provides a signal when each portion of theworkpiece W which is to be ground is in the correct longitudinalposition for grinding in alignment with the grinding wheel 17. As shownin FIGS. 1 and 2, the portion A of the workpiece W is in alignment withthe grinding wheel 17 and with a gage mechanism generally designated bythe reference numeral 20.

Reference is now made additionally to FIGS. 3, 6, 7 and 9 whichillustrate the manner in which the gage mechanism 20 is supportedadjacent the grinding wheel 17 for movement between the solid andphantom positions shown in FIG. 3. The gaging mechanism 20 is supportedby a base member 21 which is secured to a table 22, the latter of whichis best illustrated in FIGS. 3 and 6. The table 22 is in turn slidablymounted on a table slide 23 which is secured to a subbase 24. Thesubbase 24 is secured to a pedestal 25 which is mounted to the front ofthe bed 11, as is best illustrated in FIG. 1. The subbase 24 isadjustable to position the gage mechanism 20 for the maximum diameter tobe ground which controls the transverse movement of a workpiece engagingchordal type caliper 26.

The base member 21 supports a gage arm 27 which is pivotally mountedabout a pivot 28. The lowering of the arm 27 moves the caliper 26 into alower position which will permit the caliper 26 to be advanced againstthe workpiece W, as indicated in phantom outline in FIG. 7, so as tosense the diameter thereof.

Movement of the arm 27 is effected by a piston rod 30 within a hydraulicmotor or cylinder 31 for raising or lowering the caliper 26. Thehydraulic motor 31 is mounted within the base member 21, as best shownin FIGS. 3 and 7, and the piston rod 30 thereof is secured at a point 32to an arm 33 which is in turn connected at the pivot 28 to the lower endof the arm 27. A coil spring 34, which is best illustrated in FIG. 3,connects the base member 21 to an inner portion of the gage arm 27 toprovide means to raise the caliper 26 should a power failure occurduring a grinding operation.

The arm 27 supports the caliper 26 by means of two arms 35, 36, thelatter of which is longer than the former. The arms 35 and 36 areequally spaced along their lengths, but, do not form a parallelogrambecause of the longer length of the arm 36 noted heretofore whichprovides near horizontal movement of the caliper 26 when a piston rod 37within a hydraulic motor or cylinder 38 is advanced to the right asviewed in FIGS. 3 and 7.

The caliper 26 is secured to a transducer housing 40 by screws 41 in aconventional manner, as is best shown in FIG. 3. The housing 40 issupported by vertical leaf springs 42 and 43 which are secured tosupport members 44 at opposite sides of the housing 40. The supportmembers 44 and 45 are connected to the housing 40 through alignment rods46 and 47 which are in threaded engagement with said support members andlugs 48 and 49 which project from respective sides of the housing 40.

Reference is now made to FIGS. 6 and 7 which illustrate the manner inwhich the gage mechanism 20 is controlled in response to a punch card(not illustrated) to effect movement of the arm 27 and the caliper 26carried thereby toward the workpiece W. The lattermentioned meansincludes a piston 50 within a hydraulic cylinder 51, the latter of whichis secured to the subbase 24 and includes a piston rod 52 which issecured to an extension (unnumbered) of the slidably mounted table 22which carries the gage base member 21.

Air valves 54 and 55 (FIG. 6) are secured to table brackets 56 and 57,respectively, so that movement of the base member 21 to the right orleft by movement of the piston rod 52 effects the closing ofconventional pressure switches 3PS or 4PS (FIG. 6) by reduced airpressure.

The air valve 54 is open when the base member 21 is positioned to theleft as the table slide 23 secured to the subbase 24 depresses a spring60. The air valve 55 is opened when the base member 21 is positioned tothe right by the slide 23 depressing a spring 61. The air valves 54 and55 energize the pressure switches 3PS and 4PS by reduced pressure in aconventional manner to provide a signal to permit an operational cycleto start when the base member 21 and the caliper 26 are in the correctlongitudinal position for measuring the unground portion of theworkpiece W.

The upper end of the leaf springs 42, 43 are secured to a lower swivelplate 63 which is secured to an upper swivel plate 64 by a threadedscrew and swivel pin 65 (FIG. 3). The plate 64 is secured to the pivotalarms 35, 36 so that movement of the arm 27 by the motor 31 in the mannerheretofore described or movement of the piston rod 37 effects movementof the caliper 26. Fine horizontal adjustment of the caliper 26 isobtained from an eccentric member locked in the swivel plate 63. Turningof the member 70 advances or retracts the caliper 26 a small amount as anotch 71 is provided in the housing 40 which is held against theeccentric member 70 by tension of the leaf springs 42, 43.

Fine vertical adjustment of the caliper 26 may be made by adjusting aset screw 75 (FIG. 3) to increase or restrict the forward movement ofthe arm 27 when the caliper 26 is lowered by the hydraulic motor 31.

Adjustment of the alignment rods 46, 47 will permit any out ofsquareness to be corrected so that the side of caliper 26 is normal tothe axis of the workpiece W.

Reference is now made to FIG. 5 which illustrates the caliper 26including outer shoe portions through 83 on the outer edges of the gage20 which are ground to a dimension slightly under the center shoeportions 84, 85. This arrangement enables the outer shoe portions 80through 83 to be used only for checking the longitudinal position of theworkpiece while the center shoe portions 84, 85 contact the workpiecefor positioning a probe 86 with its center line passing through the axisof the workpiece W (not shown in FIG. 5) or close thereto, as shownrelative to two different diametered workpiece portions in FIG. 3. Theouter shoe portions 80 through 83 would contact a shoulder formed by alarger diameter when the workpiece W is not .cor rectly positioned withcomparison to the programmed location.

The center shoe portions 84, 85 of the gage contact the workpiece W atpoints formed by a specific angle of 106, 15 minutes and 36 secondswhich provides an 8 to 1 ratio in amplification by the gage sensingelement or probe 86.

Turning now to the electronic circuit illustrated in FIG. 8, a programsequence controller 200 is provided for producing a plurality of enablesignals which are coupled to the card reader 201 by wiring indicatedgenerally by the numeral 204. Output digital signals from the cardreader 201 are coupled to a digital to analog converter 202 via a wiring210. The digital to analog converter 202 produces an analog signal whichis coupled, via a lead 211, to a conventional summing network 203 whichalso receives an analog signal from the gage 20 via a lead 212.

The output from the summing network 203 is coupled to a coarse meter 213by a lead 214. The coarse meter 213 is arranged to produce a signal onan output wiring 215 to indicate whether or not a portion of theworkpiece W which is in engagement with the probe 86 is within the roughsize tolerance and thereby qualifying to be ground. An output from thecoarse meter 213 is also fed via a lead 216 to a fine meter 217 which,in turn, supplies an output to the wiring 215 which indicates that aportion of the workpiece W in contact with the probe 86 has reached thedesired final size.

The coarse meter 213 and the fine meter 217 also provide respectivelyvisual indications of the size of that portion of the workpiece which isin contact with the probe 86 during the qualifying and final sizeportions of an operational cycle, respectively.

As thus far described, the circuit of FIG, 8 produced signals on thewiring 215 in response 'to the programmed size, as determined solely bythe card reader 201, and the actual measurement of each workpiecediameter, as determined by the position of the probe 86. The remainderof the circuit, yet to be described, illustrated in FIG. 8 is arrangedto provide for a programmed ofiset to compensate for possible errorsbetween the programmed size and the actual measurement of each workpieceW diameter and, if desired, to provide means for correcting patterns ofsize irregularities and making minor size adjustments without changingthe card in the card reader 201.

In addition to receiving digital signals from the card reader 201, thedigital to analog converter 202 receives an analog size otTset signalfrom an analog size offset circuit 220, via a wire 221. An input to theanalog size offset circuit 220 is provided by 222 from a second digitalto analog converter 223.

The details of a particular analog size offset circuit which may be usedfor the analog size offset circuit 220, as well as the connectionsthereof to the digital to analog converters 202 and 223, is illustratedin FIG. 10 which is described in detail hereinafter.

The program sequence controller 200, in addition to supplying enablingsignals to the card reader 201 supplies enabling signals to a wiringgenerally designated by the numeral 224 which, as illustrated, consistsof five leads 225-229 which are connected respectively in parallel withthe leads 205-209 of the wiring 204. The leads 225-229 are individuallyconnected to one of five thumbwheel switches generally designated by thenumeral 230. Each of the thumbwheel switches 230 is provided with aplurality of contacts (not illustrated) which may be set by thethumbwheels of the thumbwheel switches in accordance with the desires ofan operator to provide programmed offset signals in digital form to awiring 232. As will be readily apparent to those skilled in the art,individual contacts (not illustrated) within each of the thumbwheelswitches 230 selectively pass enabling signals, which may appear on theleads 225-229, the the individual leads of the wiring 232 via isolatingdiodes, generally illustrated by the numeral 233. The individualcontacts (not illustrated) within each of the thumbwheel switches 230,depending on the setting of the thumbwheels chosen by the operator,instead of passing the enabling signal may establish a referencepotential on selected ones of the contacts (not illustrated) within thethumbwheel switches. The enabling signals, which are passed toindividual leads of the wiring 232 establish a high (1) condition onselected ones of the leads constituting the wiring 232 while other leadsare maintained at a low (0) condition thereby providing the digitalinput from the wiring 232 to the digital to analog converter 223. Thus,each of the thumbwheel switches 230 individually establish a particularoffset for respective diameters of the workpiece W so far as the amountof programmed offset is concerned.

Each of the leads 225-229, forming part of the wiring 224, is connectedto an individual one of a plurality of single-pole single-throw switchesdesignated generally by the numeral 234 which are connected via a lead235 to the digital to analog converter 223. As shown, each of thesingle-pole single-throw switches 234 is shown in an open position. Insuch a position, no enabling signal is passed to the lead 235, and thedigital to analog converter 223 provides an analog output signal on thewiring 222 of a particular polarity in accordance with the digital inputprovided from the wiring 232.

In the event an operator wishes to provide a programmed negative offsetsignal, as opposed to a programmed positive offset signal, for one orthe other of the workpiece portions of the workpiece W, he may simplyclose one of the switches 234 thereby establishing on the lead 235 asignal for reversing the output of the digital to analog converter 223by passing an enabling signal to the lead 235 from a selected one of theleads 225-229. As can be seen from the foregoing, the output from thedigital to analog converter 202 maybe modified in accordance with anoutput from the analog size offset circuit 220'which, in turn, receivesprogrammed offset signals from the digital to analog converter 223 whichmay vary in magnitude in accordance with the setting of the thumbwheelswitches 230 and in polarity'independent from the setting of individualswitches of the single-pole, single-throw switches 234.

Referring now the the circuit of FIG. 10, the digital to analogconverter 223, the analog size offset circuit 220 and the digital .toanalog converter 202, which are also illustrated in FIG. 8, are shown.The internal construction of a particular analog size ofiset circuit 220which may be used in practicing the present invention is shown indetail. The analog size offset circuit 220 includes a potentiometer 236having a first end connected to a plurality of series connectedprecision resistors Rl-R9. A second end of the potentiometer 236 issimilarly connected to a second plurality of series connected precisionresistors R1'R9'. Exemplary ohmic values for each of the precisionresistors Rl-R9 and R1'R9' are shown in FIG. 10. The ohmic value of theprecision resistor R1, as can be seen from FIG. 10, is the same as theohmic value of the resistor R1. The specific ohmic value of each of theprecision resistors R2-R9 correspond respectively to the ohmic values ofthe precision resistors R2'-R9'.

A first fixed voltage source 237 of a given polarity is connected inseries between the precision resistor R1 and one of the leads formingthe wiring 222 from the digital to analog converter 223. An oppositelypoled fixed voltage source 238 is series connected between the precisionresistor R1 and the other lead of the wiring 222 from the digital toanalog converter 223.

A switch 240, having a contact 241 connected across the precisionresistor R9, and a switch 242, having a contact 243 connected across theprecision resistor R9, are provided. The switches 240 and 242 are gangedtogether as indicated by a broken line 244. As shown, the contact 241 isopen thereby placing the precision resistor R9 in circuit and thecontact 243 is closed thereby short circuiting the precision resistor R9so as to provide a common offset signal which is coupled to the digitalto analog converter 202 via the wire 221. The signal on.the wire 221 isadded to the output from the digital to analog converter 202 whichreceives a digital input from the wiring 210 so as to modify the analogoutput appearing on the lead 21 1.

Each of the precision resistors Rl-R8 is provided respectively with acontact Kl-K8 connected in parallel therewith. Similarly, each of theprecision resistors R1'-R8 is provided respectively with a contactKl'-K8 connected in parallel therewith. A first twopole toggle switch(not illustrated) is provided for simultaneously opening the contact K1while closing the contact K1 and, conversely, for simultaneously openingthe contact K1 and closing the contact K1. A second two-pole toggleswitch (not illustrated) is provided for opening and closing thecontacts K2 and K2. Each of the pairs of contacts K3-K3' throughcontacts K8-K8 is provided with a similar toggle switch (notillustrated) for opening and closing said contacts. As shown in FIG. 10,contacts Kl -K4 and contacts K5'-I(8 are shown in an open conditionwhile corresponding contacts are shown in a closed condition. Since thevalues of the precision resistors R1-R4 correspond respectively to thevalues of the precision resistors R5'R8', the only offset provided bythe analog size otYset circuit in the condition shown, is provided bythe fact that the precision resistor R9 is in circuit while theprecision resistor R9 has been short circuited. In

the event an operator wishes to add further common offset, he needsimply to open a selected one of the additional contacts KS-K8 whileclosing the corresponding contacts K5'-K8' by selectively setting one orthe other of the toggle switches (not illustrated) associated with theselected pair of contacts. Similarly, if an operator wishes to reducethe amount of ofi'set provided by simply short circuiting the resistorR9, he may open additional ones of the contacts K1'-K4' whilesimultaneously closing additional ones of the contacts K1-K4. It will beappreciated by those skilled in the art, that by simultaneously addingand subtracting resistances from the two arms of the analog size offsetcircuit, 220 the value of the total resistance provided by the precisionresistors R1-R8 and R1-R8' remains unchanged.

OPERATION The operation of the grinding machine 10 and particularly theelectronic circuit illustrated in FIG. 8 will now be described withparticular reference to the circuitry of FIGS. 9 and 10.

In order to place the circuit of FIG. 8 in readiness for operating thegrinding machine 10 of the present invention, a programmed card whichincludes instructions for the specific size of the five diameters of theworkpiece portions A-E is placed within the card reader 201. Thethumbwheel switches 230 are each positioned so as to provide all lowsignals (0) to each of the leads constituting the wiring 232. Each ofthe switches 234 is set in an open position, as shown in FIG. 8.

With the thumbwheel switches 230 offset to provide low (0) signalcondition on each of the leads forming the wiring 232, the digital toanalog converter 223 has a zero output and no current attributable to ananalog signal from the digital to analog converter 223 flows through thewiring 222. As thus far described, the circuit of FIG. 8 will notprovide any programmed input to the analog size offset circuit 220.

Referring now to FIG. 10, the switches 240 and 242 are initiallypositioned so that both are open, as illustrated by the broken linesassociated respectively with the contacts 241 and 243. In such aposition, the movable contact associated with the potentiometer 236 isadjusted so that a zero output appears on the wire 221. The switches 240and 242 are then moved to the position shown in solid line, therebyclosing the contact 243 while maintaining the contact 241 open. It willbe appreciated, that in the just-mentioned position, the circuitconstituted by the precision resistors Rl-R9 and Rl'-R9 becomesunbalanced, a greater resistance being associated in that armconstituted by the precision resistors Rl-R9. As will be readilyunderstandable to those skilled in the art, a voltage appears on thewire 221 thereby providing a given ofiset signal to the digital toanalog converter 202 which would provide a predictable given oversizefor each of the ground diameters. For example, in a practical embodimentthe predictable oversize could be 0.005 inch. In many instances, nofurther adjustment of the analog size offset circuit 220 is needed ordesirable.

On the other hand, an operator may modify the common offset provided bythe analog size offset circuit 220 by simply either adding orsubtracting resistance from the arm of the resistive circuit constitutedby the resistors Rl-R8 while simultaneously either subtracting or addingcorresponding resistors in that arm constituted by the precisionresistors R1 '-R8.

It will be appreciated by those skilled in the art that thejust-discussed adjustments of the analog size offset circuit 220 willserve to provide a given common offset for each and every diameterportion A-E of a workpiece. As thus far described, the circuitry of thepresent invention does not provide an offset which takes into accountthe varying fiexural characteristics of a workpiece. In thesecircumstances, it is likely that different portions A-E of the workpieceW may vary somewhat in actual oversize.

With the workpiece W placed in the machine and with a selector switchSS3 (FIG. 9) set in its closed automatic position, the carriage 12automatically positions the left-hand portion A of the workpiece W infront of the grinding wheel 17 and the gage mechanism 20 is positionedlongitudinally in response to the programmed card in the card reader 201(FIG. 8).

The gage mechanism 20 is positioned to the left or right to align thecaliper 26 with the side of the grinding wheel 17 adjacent the shoulderof a larger diameter portion of the workpiece W through a reset button(not illustrated) as part of the setup operation.

The gage mechanism 20 is positioned to the left unless contact K6Y isclosed from the card reader 201 as GAGE LEFT relay 7CR is energizedthrough cycle selector switch SS3 and normally closed contacts 8CR1 and30CR5. Upon the energization of the GAGE LEFI relay 7CR a contact 7CR!closes to energize a solenoid 4SOL (FIGS. 7 and 9) which shifts a valve90 (FIG. 7) to the left. Hydraulic pressure is directed from a tank 91by a pump 92 to the valve 90 through lines 93, 94 and 95. Pressure line96 directs pressure from the valve 90 through a throttle valve 97 to therod end of the hydraulic cylinder 51 (figs. 6 and 7). Piston 50 withinthe cylinder 51 is moved to the left which positions the base member 21and the caliper 26 in line with the left edge of the grinding wheel 17,at which point the pressure switch 3PS (FIGS. 6 and 9) is closed byreduced pressure as the air valve 54 is opened in the manner heretoforedescribed. The caliper 26 is positioned to the right when a GAGE RIGHTrelay 8CR is energized through the selector switch SS3 when contact K6Yis closed from the card reader 201 and normally closed contacts 30CR6.

Contact 8CR2 closes to energize solenoid SOL and shifts the valve 90(FIG. 7) to the right. Hydraulic pressure from the line 95 through thevalve 90 directs hydraulic pressure through a line 98 and through athrottle valve 100 therein to the head end of the cylinder 51.

Piston 50 is moved to the right to effect movement of the base 21 andthe caliper 26 in the same direction until pressure switch 4PS (FIGS. 6and 9) is closed by reduced pressure as air valve 55 is opened.

The infeed lever 19 (FIG. 1) is moved to the advance position tocondition the wheel support or wheel head 29 which carries the grindingwheel 17 for infeed movement during the cycle, after the diameter to beground has been qualified.

Limit switch 4LS is closed from said movement of infeed lever 19 toenergize the WHEELHEAD CONDI- TIONING relay 28CR (FIG. 9) causingcontact 28CR1 to close thus providing which is closed as the wheelsupport or wheel head 29 is in its retracted position.

Contact 28CR2 closes to energize the CYCLE START relay 29CR through GAGELEFT pressure switch 3PS or GAGE RIGI-It pressure switch 4P8, one ofwhich was closed by reduced pressure when he base member 21 and thecaliper 26 were longitudinally positioned, in the manner heretoforedescribed.

Contact 29CR1 closes in the circuit with INFEED relay 30CR.

Contact 29CR2 closes to energize the GAGE UP & DOWn relay 40CR to lowerthe caliper 26 through the mechanism heretofore described. Contact 40CR1energizes a solenoid 18SOL which shifts valve 102 (FIG. 7) to the left,wherein hydraulic pressure is directed from the pump 92 to said valve102 through the lines 93, 94 and a line 103. A line 104 directs pressurefrom the valve 102 through a throttle valve 105 and a line 106 to therod end of the cylinder 31. This causes the piston rod 30 to move to theright, as viewed in FIG. 7, to pivot the arm 33 clockwise. Arm 27likewise pivots clockwise and downwardly as piston rod 30 moves to theright, which lowers the caliper 26 to generally the phantom outlineposition shown in FIG. 7, although spaced leftward from the workpiece W.Hydraulic fluid is discharged from the head end of the cylinder 31through line 87, throttle valve 88, line 89, valve 102 and return line109 to the tank 91.

GAGE ON limit switch 10LS is closed when the caliper 26 is lowered toenergize GAGE OFF relay 41CR.

Upon the energization of the GAGE OFF relay 41CR, the contact 41CR1 isclosed which completes a circuit to energize GAGE ON & OFF relay 46CRthrough contact 35CR2 which was closed when the wheel support or wheelhead 29 was retracted.

Contact 46CR1 closes to provide a holding circuit for GAGE ON & OFFrelay 46CR through contact 35CR2.

Contact 46CR2 closes to provide a holding circuit with GAGE ON & OFFrelay 46CR through normally closed contact 39CR2 and contact 30CR4 whichcloses during rapid infeed.

Contact 46CR3 closes to energize GAGE 0N & OFF solenoid 20SOL whichshifts a valve 107 to the left, as viewed in FIG. 7.

Hydraulic pressure is directed by the pump 92 to the valve 107 throughlines 93 and 108, and a line 110 directs pressure to the head end of thehydraulic motor 38 which moves the piston rod 37 to the right, as againviewed in FIG. 7, which near horizontal direction as the arms 35, 36 arepivoted. The probe or sensing element 86 is thus brought into contactwith the workpiece W with its center line passing through or near theaxis of the workpiece W, irrespective of the particular diameterthereof, as indicated by a second workpiece W in phantom outline in FIG.3. This occurs because of the longer length of the arm 36 as compared tothe arm 35 which brings the center shoe portions 84, 85 into contactwith the workpiece W at equal arcuate distance from the point of contactof the probe 86 against the workpiece W. At this time the gage mechanism20 is in position to perform a qualifying" function to determine theunground dimension of the workpiece in comparison to a preset dimensionof a card in the card reader 201, modified by the offset signal which isprovided, via the wiring 221, to the digital to analog converter 202which processes the data provided from the card reader 201 via thewiring 210.

A conventional summing network 203 (FIG. 8) receives a signal from theprobe 86 of the caliper 26, as well as a size signal, modified toprovide offset, from the digital to analog converter 202. The output ofthe summing network 203 is fed to a coarse meter 213 which produces asignal to indicate whether or not the portion to be ground is within therough size tolerance for a particular oversize diameter of the workpieceW which is to be ground. When the diameter to be ground is within thediameter is qualified or approved and a signal closes a normally opencontact QR (FIG. 9) to energize QUALIFICATION relay 48CR throughnormally closed contact 41CR2.

Contact 48CR1 closes to energize INFEED relay 30CR through normallyclosed WHEELHEAD OUT limit switch 6LS, contact 29CR1 and normally closedcontact 50CR1 to efl'ect further movement of the wheel support or wheelhead 29 and the grinding wheel 17 carried thereby toward the workpiece Wto begin Contact 30CR1 is grinding cycle.

Contact 30 CR 1 is closed to provide a holding circuit with INFEED relay30CR. Contact 30CR2 is closed to energize INFEED solenoid 14SOL whichadvances the wheel head 29 and the grinding wheel 17 carried thereby.

Normally closed contacts 30CR5 and 30CR6 open to deenergize relay 7CR or8CR and solenoid 4SOL or SSOL is deenergized which moves the GAGESI-Iift valve 90 (fig. 7) to the inoperable or central position.Hydraulic pressure to the cylinder 51 is eliminated and the air valve 54or 55 is reset by the spring 60 or 61, respectively, to reset said valveand to position the gage mechanism 20, to provide clearance between theside of the shoulder and the side of the caliper 26 adjacent thereto.

The forward movement of the wheel support or wheel head 29 opens wheelhead BACK limit switch 8LS which was held closed when the wheel supportor wheel head 29 was retracted against a solid stop by hydraulicpressure.

Wheelhead back relay 35CR is deenergized as the wheel head 29 isadvanced.

Contact 35CR3 is opened which deenergizes GAGE ON relay 39CR and caliper26 is retractedfrom the workpiece W.

If the dimension of the portion to be ground is too large and outsidethe qualifying range indicated by the circuitry of FIG. 8, the gagecontact QR will not be closed and the QUALIFICATION relay 48CR will notbe energized. The wheel head 29 will therefore not be advanced ascontact 48CR1 of the INFEED circuit will remain open.

If the dimension of the unground portion of the workpiece W to be groundis undersize, the caliper 26 provides a signal which is combined in themanner heretofore described with the signal from .the card reader 201and this comparison signal is received by a fine meter 217 (FIG. 8)which, in turn, produces a size signal to close contact SR to energizeON SIZE relay 50CR.

Normally closed contact 50CR1 is opened to prevent INFEED RELAY 30CRfrom being energized.

When the unground workpiece is at size or undersize, the wheel supportor wheel head 29 is not advanced as QUALIFICATION relay 48CR is neverenergized. Therefore, contact 48CR1 is never closed to energize INFEEDrelay 30CR except upon the closing of the contact OR in the mannerheretofore described.

The caliper 26 is advanced during the grinding operation when a GAGE ONcam (not shown) on hand wheel opens a limit switch contact 9LS1. TheGAGE ON relay 39CR is deenergized and wheel head 29 is retracted.

Limit switch contact 9LS2 is closed to complete a circuit to energizethe GAGE ON & OFF relay 46CR through contact 30CR4.

Contact 46CR2 closes to provide a holding circuit with the GAGE ON & OFFrelay 46CR through closed contacts 39CR2 and 30CR4. Contact 46CR3 isclosed to energize GAGE ON & OFF solenoid SOL which shifts the valve 107to the left (FIG. 7).

Fluid pressure is then directed from the valve 107 to the head end ofthe cylinder 38 through the line 110 causing the piston rod 37 toadvance to the right as viewed in FIG. 7 to again position the caliper26 and the probe 86 onto the workpiece W.

During the remaining portion of the grinding operation the probe 86sends a continuously changing signal corresponding to the change in thedimension of the workpiece W to the summing network 203. The

. specific construction of the probe 86 and a transducer associatedtherewith which may be used in machine tools using the present inventionis fully disclosed in commonly assigned application Ser. No. 824, 433,filed May 14, 1969, in the name of Kurt M. Gebel, which was abandoned infavor of a continuation application filed Sept. 8, 1971. It is to beunderstood, however, that the invention may be used with probes andtransducers of different construction.

The summing network 203 also receives a signal from the card reader 201,as heretofore described, or from conventional manual dial switches 111when the card reader 201 is not used. The summing network 203 representsthe desired finished dimension of the particular workpiece portion beingground modified in accordance with the setting of the analog size offsetcircuit 220.

The progress of the grinding operation is shown respectively on thecoarse and fine meters 213 and 217, which are arranged in series tovisually show when the diameter is at finish size.

A near size signal from the gage mechanism 20 through the fine meter 217closes a contact NSR to energize NEAR SIZE relay 49CR. A normally closedcontact (not shown) from relay 49CR opens to deenergize the incrementfeed, and spark out is then effected until ON SIZE contact SR is closedfrom the gage mechanism 20 to energize the ON SIZE relay 50CR.

The normally closed contact 50CRl is opened which energizes INFEED relay30CR to retract the grinding wheel 17 by retraction of the wheel supportor wheel head 29.

The operation of the grinding machine 10 and the gage mechanism 30CRassociated therewith is continually repeated in the manner heretoforedescribed until each of the workpiece W portions A through E 20 beenqualified and have been ground to a predetermined oversize, or untilsuch time that prior to grinding one of the portions a qualificationsignal is not received from the circuit of FIG. 8 and the grindingoperation is terminated by the prevention of wheel head 29 advancement.

The actual diameter of the workpiece W portions A through E are thenindependently determined. Each of the workpiece W portions A through Eare expected to be oversize because of the previous setting of theanalog size offset circuit 220. If in fact, one or more of the workpiecegrinding portions A through E is not oversize, possible furtheradjustments of the contacts Kl-KS and K1'K8' is indicated so as to addadditional resistance to the arm constituted by the precision resistorsRl-R9 and simultaneously deleting resistance from the arm constituted bythe precision resistors R 1 '-R9. In most instances, however,particularly when an operator has had experience with similarworkpieces, all of the workpiece W portions A through B will beoversize; however, the portions A through B will not all be exactlyoversize by the same amount.

Thumbwheel switches 230 are then adjusted so as to provide appropriatedigital signals to the wiring 232 in response to enabling signals whichappear on each of the leads 225-229 from the program sequence controller200, which provides, contemporaneously with the appearance of an enablesignal on each of the leads 225-229, a grinding signal for each of theworkpiece W portions A through E, respectively. It is accordingly, clearthat the thumbwheel switches 230 can each be set to provide specificdigital signals on the output wiring 232 to the digital to analogconverter 223 which are converted therein and appear as an analog signalon the wiring 222 thus modifying the current flow in the resistivenetwork of the analog size offset circuit 220. In effect, the outputfrom the digital to analog converter 223 is connected in series with thetwo voltage sources 237 and 238. As thus far described, the digital toanalog converter 223 will provide modification of the output from theanalog size offset circuit 220 which appears on the wiring 221 of agiven polarity or direction. The thumbwheel switches 230 are eachindividually set by an operator to a particular value corresponding tothe amount each of the workpiece W portions A through E differs in itsoversize from that desired by the setting of the resistive networkwithin the analog size offset circuit 220.

As thus far described, the setting of the thumbwheel switches 230 serveto provide for the appearance of digital signals on the wiring 232which, when converted to analog signals within the digital to analogconverter 223 and appear on the wiring 222, serve to provide additionalpositive offset since the output from the digital to analog converter223 is of a given polarity. Since some of the workpiece W portions Athrough E may be too large instead of too small, it is desirable toprovide for the appearance of an enable signal on the lead 235 whichwill serve to reverse the output from the digital to analog converter223 in the event a programmed negative offset is desired for anyparticular diameter. To accomplish the reversal of the output from thedigital to analog converter 223, individual ones of the single-polesingle-throw switches 234 are closed so as to provide selectively aplurality reversing enable signals on the wiring 222 upon the appearanceof an enable signal on any of the leads 225-229 during the grinding ofworkpiece portions A through E, respectively.

The switches 240 and 242 are opened so as to open both the contact 241and the contact 243 and additionally the toggle switches (notillustrated) associated with the contacts Kl-K8 are positioned so thatthe contacts are opened and closed as shown in FIG. 10 therebyestablishing the analog size offset circuit 220 in its initialcondition. In such a condition, the circuitry of the present inventionwill respond to a program and grind the workpiece W portions A through Eexactly to the programmed size since a modifying programmed offsetsignal is processed through the analog size offset circuit 220 from thedigital to small converter 223 without any additional common offset oroversize being provided. During the remaining portion of the grindingoperation the probe 86 sends a continuously changing signalcorresponding to the change in dimension of the workpiece W to thesumming network 203 which receives an additional analog signal from thedigital to analog converter 202 in accordance with firstly the outputfrom the card reader 201 and secondlyin accordance with the output fromthe digital to analog converter 223 which supplies specific and distinctoffset signals during the grinding of each of the workpiece portions Athrough E to take into account the different flexural characteristicsprocessed the workpiece W portions A through B being ground. 7

It will be appreciated by those skilled in the art that the thumbwheelswitches 230 and the single-pole single-throw switches 234 may bemanipulated to provide for grinding individual workpieces W orindividual workpiece W portions A through E a predetermined amountoversize or undersize without changing or modifying the card within thecard reader 201. F urthermore, the thumbwheel switches 230 and thesingle-pole single-throw switches 234 may be utilized to correctpatterns of size irregularities which may occur during an extendedperiod of time without changing or modifying the card within the cardreader 201.

While preferred forms and arrangements of parts have been shown in thethumbwheel invention, it is to be clearly understood that variouschanges in details and arrangement of parts may be made withoutdeparting from the spirit and scope of this invention as defined in theappended claims.

What is claimed is:

1. In a grinding machine,

a. a bed,

b. a workpiece support on said bed having means for supporting aworkpiece,

a workpiece wheel support, means for effecting relative transversemovement of said supports,

. gage means positionable to engage portions of a workpiece to be groundand including means for generating a size signal indicative of the sizeof that portion of a workpiece with which engagement is made,

f. means for providing signals indicative of desired sizes for saidportions of a workpiece,

g. means for providing individual offset signals for each of saidportions of a workpiece, and

h. means responsive to said size signal, said signals indicative ofdesired sizes for said portions of a workpiece and said individualoffset signals for each of said portions of a workpiece for controllingsaid means for effecting relative transverse movement of said supports.

2. A grinding machine according to claim 1, wherein said means forproviding individual offset signals for each of said portions of aworkpiece is adjustable to provide an individually adjustable offsetsignal for each of said portions of a workpiece.

' said means for providing individual offset signals includes a firstmeans for providing a first predetermined common offset signal, a secondmeans for providing an individual second offset signal during grindingof each of said portions of a workpiece, and means for combining saidfirst predetermined common offset signal and each individual secondoffset signal to establish said individual offset signals.

5. A grinding machine according to claim 4, wherein said first means isselectively operable to remove said first predetermined common offsetsignal whereby only each of the individual second offset signals provideoffset.

6. A grinding machine according to claim 4, wherein said second meansfor providing an individual offset signal is adjustable for providingdiffering amounts of offset for said portions of a workpiece.

7. A grinding machine according to claim 6, wherein said second meansfor providing an individual offset signal includes means for selectivelyreversing the direction of offset for each of said portions of a.workpiece.

8. A grinding machine according to claim 1, wherein said means forproviding individual offset signals for each of said portions of aworkpiece is adjustable for providing differing amounts of offset forsaid portions of a workpiece. I

9. A grinding machine according to claim 8, wherein said means forproviding individual offset signals for each of said portions of aworkpiece includes means for selectively reversing the direction ofoffset for each of said portions of a workpiece.

10. A grinding machine according to claim 1, wherein said means forproviding individual offset signals comprise a digital to analogconverter, means coupled to said digital to analog converter forproviding predetermined digital signals thereto correspondingrespectively to desired offset for each of said portions of a workpiece,and an analog size offset circuit coupled to receive an output from saiddigital to analog converter.

11. A grinding machine according to claim 10, including a second digitalto analog converter, said second digital to analog converter having afirst input coupled to said means for providing signals indicative ofdesired sizes for said portions of a workpiece, the last said meansbeing operative to provide digital signals indicative of the desiredsizes for said portions of a workpiece; said second digital to analogconverter having a second input coupled to receive an output from saidanalog size offset circuit for modifying an analog output signal fromsaid second digital to analog converter; and a summing network coupledto said second digital transverse movement of said su ports.

1 A ndmg machine according to claim 11,

wherein the output from said summing network is coupled to means forproducing qualifying signals and on size signals.

13. A grinding machine according to claim 12, wherein said means forproducing qualifying signals and on size signals include meter means.

14. A grinding machine according to claim 13, wherein said meter meanscomprise a meter for indicating coarse dimensions and a meter forindicating fine dimensions.

15. A grinding machine according to claim 10, wherein said analog sizeoffset circuit includes means for providing a common offset signal andfor processing said output from said digital to analog converter.

16. A grinding machine according to claim 15, wherein said means for.providing a common offset signal is adjustable whereby the common offsetsignal may be reduced to zero.

17. In a machine tool,

a. means for effecting relative movement between a tool support and awork support of a machine tool in order to control stock removal from awork.- piece carried by the work support,

b. means for controlling said means for effecting relative movementincluding program means for providing a plurality of distinct relativemovements of said tool support and said work support during a machineoperation, and

. offset means coupled to said means for controlling including means forautomatically providing thereto individual offset signals for each ofsaid distinct relative movements whereby an individual amount of offsetmay be provided during each of said distinct relative movements betweensaid tool support and said work support.

18. A machine tool according to claim 17, wherein said offset means isadjustable for providing individually adjustable offset signals.

19. A machinetool according to claim 17, wherein said offset meansincludes a first means for providing a first predetermined common ofisetsignal, a second means for providing an individual second offset signalduring each of said distinct relative movements and means for combiningsaid first predetermined common offset signal and each individual secondoffset signal to establish said individual offset signals.

20. A machine tool according to claim 19, wherein said first means isselectively operable to remove said first predetermined common offsetsignal whereby only each of the individual offset signals provideoffset.

21. A machine tool according to claim 17, including means forselectively reversing the direction of offset for each distinct relativemovement.

* l t l

1. In a grinding machine, a. a bed, b. a workpiece support on said bedhaving means for supporting a workpiece, c. a workpiece wheel support,d. means for effecting relative transverse movement of said supports, e.gage means positionable to engage portions of a workpiece to be groundand including means for generating a size signal indicative of the sizeof that portion of a workpiece with which engagement is made, f. meansfor providing signals indicative of desired sizes for said portions of aworkpiece, g. means for providing individual offset signals for each ofsaid portions of a workpiece, and h. means responsive to said sizesignal, said signals indicative of desired sizes for said portions of aworkpiece and said individual offset signals for each of said portionsof a workpiece for controlling said means for effecting relativetransverse movement of said supports.
 2. A grinding machine according toclaim 1, wherein said means for providing individual offset signals foreach of said portions of a workpiece is adjustable to provide anindividually adjustable offset signal for each of said portions of aworkpiece.
 3. A grinding machine according to claim 1, wherein saidmeans for providing individual offset signals for each of said portionsof a workpiece is operative to provide for grinding each of saidportions of a workpiece a preselected amount of oversize.
 4. A grindingmachine according to claim 1, wherein said means for providingindividual offset signals includes a first means for providing a firstpredetermined common offset signal, a second means for providing anindividual second offset signal during grinding of each of said portionsof a workpiece, and means for combining said first predetermined commonoffset signal and each individual second offset signal to establish saidindividual offset signals.
 5. A grinding machine according to claim 4,wherein said first means is selectively operable to remove said firstpredetermined common offset signal whereby only each of the individualsecond offset signals provide offset.
 6. A grinding machine according toclaim 4, wherein said second means for providing an individual offsetsignal is adjustable for providing differing amounts of offset for saidportions of a workpiece.
 7. A grinding machine according to claim 6,wherein said second means for providing an individual offset signalincludes means for selectively reversing the direction of offset foreach of said portions of a workpiece.
 8. A grinding machine according toclaim 1, wherein said means for providing individual offset signals foreach of said portions of a workpiece is adjustable for providingdiffering amounts of offset for said portions of a workpiece.
 9. Agrinding machine according to claim 8, wherein said means for providingindividual offset signals for each of said portions of a workpieceincludes means for selectively reversing the direction of offset foreach of said portions of a workpiece.
 10. A grinding machine accordingto claim 1, wherein said means for providing individual offset signalscomprise a digital to analog converter, means coupled to said digital toanalog converter for providing predetermined digital signals theretocorresponding respectively to desired offset for each of said portionsof a workpiece, and an analog size offset circuit coupled to receive anoutput from said digital to analog converter.
 11. A grinding machineaccording to claim 10, including a second digital to analog converter,said second digital to analog converter having a first input coupled tosaid means for providing signals indicative of desired sizes for saidportions of a workpiece, the last said means being operative to providedigital signals indicative of the desired sizes for said portions of aworkpiece; said second digital to analog converter having a second inputcoupled to receive an output from said analog size offset circuit formodifying an analog output signal from said second digital to analogconverter; and a summing network coupled to said second digital toanalog converter for receiving said analog output therefrom and to saidgage means for receiving the size signals therefrom, said summingnetwork having an output coupled to said means for effecting relativetransverse movement of said supports.
 12. A grinding machine accordingto claim 11, wherein the output from said summing network is coupled tomeans for producing qualifying signals and on size signals.
 13. Agrinding machine according to claim 12, wherein said means for producingqualifying signals and on size signals include meter means.
 14. Agrinding machine according to claim 13, wherein said meter meanscomprise a meter for indicating coarse dimensions and a meter forindicating fine dimensions.
 15. A grinding machine according to claim10, wherein said analog size offset circuit includes means for providinga common offset signal and for processing said output from said digitalto analog converter.
 16. A grinding machine according to claim 15,wherein said means for providing a common offset signal is adjustablewhereby the common offset signal may be reduced to zero.
 17. In amachine tool, a. means for effecting relative movement between a toolsupport and a work support of a machine tool in order to control stockremoval from a workpiece carried by the work support, b. means forcontrolling said means for effecting relative movement including programmeans for providing a plurality of distinct relative movements of saidtool support and said work support during a machine operation, and c.offset means coupled to said means for controlling including means forautomatically providing thereto individual offset signals for each ofsaid distinct relative movements whereby an individual amount of offsetmay be provided during each of said distinct relative movements betweensaid tool support and said work support.
 18. A machine tool according toclaim 17, wherein said offset means is adjustable for providingindividually adjustable offset signals.
 19. A machine tool according toclaim 17, wherein said offset means includes a first means for providinga first predetermined common offset signal, a second means for providingan individual second offset signal during each of said distinct relativemovements and means for combining said first predetermined common offsetsignal and each individual second offset signal to establish saidindividual offset signals.
 20. A machine tool according to claim 19,wherein said first means is selectively operable to remove said firstpredetermined common offset signal whereby only each of the individualoffset signals provide offset.
 21. A machine tool according to claim 17,including means for selectively reversing the direction of offset foreach distinct relative movement.